Frequency overlay system is defined as a system where a base station divides the available frequency bandwidth into multiple frequency bands and allocates the resource of one or more frequency bands to a mobile station depending on the capacity of the mobile station.
Accordingly, the frequency overlay system is advantageous to support the mobile stations operating with various bandwidths.
In the frequency overlay system, the base station divides the radio resource into multiple Frequency Assignments (FAs) and allocates the resource of one or more FAs to a mobile station depending on the bandwidth supported by the mobile station. For instance, assuming a frequency overlay system operating with 20 MHz bandwidth and supporting mobile stations operating with 10 MHz and 20 MHz bandwidths respectively, the base station allocates resource of a single FA to the 10 MHz mobile station and resource of 2 FAs to the 20 MHz mobile station.
In the frequency overlay system, a base station generates and transmits a resource allocation information message per FA such that, in order to allocate resource of multiple FAs, the same number of resource allocation information messages are transmitted to the mobile station. That is, when a mobile station is allocated transmission resources of FA1 and FA2, the base station sends the mobile station two resource allocation information messages for the respective FA1 and FA2. Accordingly, the mobile station allocated multiple FAs must receive and decode all the resource allocation information messages transmitted separately for the respective FAs, thereby increasing the decoding complexity and resource allocation information message overhead in proportion of the number of the allocated FAs.